Do Breast Implants Feel Natural?

In general, silicone gel-filled implants feel more natural than saline because the consistency is closer to that of breast tissue. The less of your own body tissue (fat layer, breast tissue) the more important it is. With more coverage, saline implants may be perfectly fine.
There are basically 2 types of silicone implants in the U.S.: Mentor Memory gel, and Allergan Natrelle are very similar, with a natural feeling cohesive gel, and the other type is the "gummy bear" which is Mentor's CPG and Allergan's Style 410. Those are firmer, shaped implants, and there is some debate about how natural the feel is. In any case, they are not yet FDA-approved though we anticipate it should be soon.

Choosing an appropriate sized implant and placing the implant under the muscle to give more tissue coverage will give you a more natural feeling breast.  Cohesive gel implants, although more expensive, do have a more natural feel in comparision so their saline counterparts.